Green iguanas (Iguana iguana) are an established, non-native species across South and Central Florida, primarily due to the exotic pet trade and accidental releases. The subtropical climate allows these large, adaptable lizards to thrive and expand their range, creating a dynamic ecological situation. Understanding their specific diet is fundamental to grasping their impact on the local environment and the challenges they present to Florida residents. While recognized globally as herbivores, their foraging habits are influenced by the abundance of ornamental plants, flowers, and fruits, leading to a highly localized and opportunistic menu.
Primary Herbivorous Diet in Florida
The foundation of the wild green iguana’s diet in Florida is plant matter, consisting of foliage, flowers, and fruits, all readily available in the state’s lush, tropical landscapes. These reptiles possess specialized teeth and strong jaws adapted for shearing through tough plant material, making them highly efficient herbivores. Their feeding preference often targets soft, nutrient-rich parts of plants, leading to significant damage to common residential landscaping.
Iguanas show a distinct preference for the blossoms of many popular ornamental plants, including hibiscus, roses, and orchids, often devouring the entire flower heads. They also consume the leaves and new shoots of various shrubs and trees, sometimes defoliating entire branches. They readily consume soft fruits like mangos, bananas, berries, and figs when accessible, though they tend to avoid citrus fruits. The destruction caused by this targeted herbivory is a primary concern for homeowners and commercial growers.
Opportunistic Feeding and Dietary Changes
While adult iguanas maintain a predominantly herbivorous diet, their feeding behavior is highly opportunistic and shifts significantly throughout their life cycle, contributing to their invasive success. Juvenile iguanas require a higher percentage of protein for rapid growth and often consume small invertebrates, such as insects and tree snails, supplementing their plant-based intake. This omnivorous phase provides the necessary building blocks for them to reach adult size.
Adult iguanas, though primarily plant eaters, will consume animal material when the opportunity arises, distinguishing them from strict herbivores. They have been documented preying on bird eggs and small nestlings and will also scavenge carrion to obtain protein. A unique and necessary dietary habit for hatchlings is the consumption of adult iguana feces. This provides the gut microflora required to efficiently digest the fibrous plant material that forms the bulk of their adult diet.
Impact of Foraging and Human Feeding Guidance
The foraging habits of wild iguanas result in significant ecological and structural damage across Florida’s coastal areas. Their consistent feeding on native and endangered plant species can disrupt local ecosystems, and their consumption of eggs from ground-nesting birds poses a threat to native wildlife populations. Furthermore, the iguanas’ habit of digging extensive burrows for nesting and shelter undermines human infrastructure, contributing to the erosion and collapse of seawalls, sidewalks, and building foundations.
The presence of iguanas is often amplified by human interaction, which is why wildlife experts advise against feeding these reptiles. Human foods, such as bread, processed foods, and even certain greens like iceberg lettuce, are detrimental to their long-term health. These items offer poor nutritional value and, in the case of inappropriate protein sources like pet food, can lead to kidney damage and metabolic bone diseases due to an imbalanced calcium-to-phosphorus ratio. Feeding them also concentrates populations in residential areas, increasing the risk of property damage and exposure to Salmonella, which the lizards can carry and transmit through their droppings.